1. Field of the Invention
The present invention relates to an apparatus for pulverizing aggregate masses of frangible materials such as compacted soil, hardpan, rocks and the like, and more particularly to such an apparatus which provides an earth pulverizing rotor assembly mounted on a frame adapted to be carried by a tractor or the like for earth traversing movement and having a grid providing a strike plate or anvil portion adapted to be brought into engagement with the frangible materials to urge the materials into engagement with the rotor to impact the frangible materials against the strike plate portion whereby the masses of materials are fragmented.
2. Description of the Prior Art
It has long been known that many types of soils have a tendency to compact and form hardpan over the course of time when exposed to vehicular traffic and repeated applications of moisture, such as rain or water used for irrigation. Consequently, in order that such soils once compacted may be used for agricultural purposes, it is often necessary to fragment the substantially cohesive mass of the soil and to reduce the size of the resultant fragmented aggregate masses sufficiently to permit the cultivation and agricultural use of the soil.
It has also long been known that many earth surface areas have little inherent utility for agricultural purposes, due to the presence of rocks and other debris strewn thereon or incorporated therein. While some of such materials deposited on the surface of a given area may be removed therefrom by raking or the like, the removal of rocks and other aggregate masses from subsurface soils has long been known to be a time-consuming, laborious and generally ineffective task employing conventional apparatuses and implements.
A number of apparatuses have been proposed for purposes of pulverizing large fragments of hardpan soil, rocks, and other cohesive or aggregate masses, such as asphaltic roadway sections, deposited on or below earth surfaces. One such apparatus is that disclosed in my prior U.S. Pat. No. 3,409,088, directed to an apparatus for scarifying and pulverizing compacted soil and the like. My prior apparatus provided a power-driven cultivating rotor having a plurality of spaced, radially-extended teeth inclined forwardly in relation to the direction of rotor rotation and a shroud having an arcuate, reticulate, particle-size control grid mounted in the shroud with the grid formed on a radius greater than the rotor to form a crescent-shaped hammer mill area between the grid and the rotor to force material fragments too large to pass through the grid into the spaces between the teeth for transport over the rotor and to cause their gravitational and centrifugal discharge ahead of the rotor for further engagement by the teeth until sufficiently reduced in size to pass through the grid. The shroud and rotor were carried on a mobile frame mounted for earth traversing movement. In operation, large masses of aggregate soil previously ripped by a ripper carried on the frame, pass between the transversely spaced ripper teeth and are contacted by the teeth of the rotor whereby they are accelerated rearwardly to be discharged from the rotor teeth to impinge against the grid. The shroud and grid were carried substantially entirely rearwardly of the periphery of the rotor with the lowermost portions of the shroud and grid carried in trailing relation to the lowermost portion of the rotor periphery. Therefore, effective pulverizing of aggregate masses was largely dependent upon such masses first being dug from the soil by the rotor and thrown backward toward the grid.
While my prior apparatus was effective in a number of environments, it was found in practice that the apparatus had to be moved forwardly at a relatively slow pace during earth traversing movement deployed in an operative attitude to permit aggregate masses carried by the rotor into the hammer mill area to be repeatedly impacted by the rotor teeth and thrown against the grid. It was found that effective cultivation of earth surfaces having large quantities of very hard aggregate masses, such as rocks and broken hardpan, was only made possible by making multiple passes along a selected path to effect a degree of substantially homogeneous pulverizing sufficient to render the earth so pulverized suitable for agricultural purposes or earth grading.
Further, it was found that the crescent-shaped hammer mill area defined by the periphery of the rotor and the arcuate grid did not permit the optimum utilization of the pulverizing effect of the apparatus in a variety of soil environments. Moreover, it was discovered that compensation for wear of the rotor teeth was not generally effectively compensated for by adjustment of the arcuate grid, thus necessitating frequent rebuilding of the outermost portions of the teeth as they became worn down.
Therefore, it has long been known that it would be desirable to have an apparatus for pulverizing compacted soil and other aggregate cohesive masses of frangible materials, such as rock or asphalt, deposited on or below earth surfaces which is capable of pulverizing even the hardest of such compacted masses with an efficiency and a resulting homogeneity of pulverized material heretofore unattainable employing conventional implements. Further, it has long been known that it would be desirable to have such an implement which is capable of cultivating soil and the like at a variety of depths and which is adjustable to permit adaptation thereof for use in a variety of work environments. Moreover, it has also long been known that it would be desirable to have such an apparatus which is adapted to be constructed of sufficiently compact dimensions to permit the operation thereof in the cultivation of soils in vineyards, orchards, and other agricultural environments wherein preexisting plant growth defines substantially confined and narrow available paths of travel.